CENTREVILLE, Va. — A race to define Obamacare to the masses began today between the stacks at the Centreville Library. Over pizza in Decatur, Texas. And with a glass of wine in Naples, Fla.

Dozens of communities around the country hosted pro-Obamacare events, convened by the president’s foot soldiers at Organizing for Action. The series is the first salvo in what is fixing to be a month of high-stakes health care spin. When Congress returns from its summer recess in early September, there will be less than a month until Obamacare’s most sweeping coverage programs start signing up customers in new health insurance exchanges.

In the meantime, pro- and anti-Obamacare advocates are plotting to fill the silence any way they can.

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That means gatherings like today’s in Centreville — although the slow start here is probably not what OFA organizers had in mind. After a scheduling snafu over the start time, a few people showed up and left before it actually started. Just one volunteer stayed to help work the phone bank for the health law, and the event’s organizer bolted after 20 minutes — although he was bound for another Obamacare event, a house party.

The poor turnout here in Centreville wasn’t necessarily indicative of what’s happening across the country at other OFA events Sunday afternoon and evening, which coincide with President Barack Obama’s birthday. OFA sent out pictures of bigger and more enthusiastic turnout elsewhere, including some events in places like Ohio, Florida and Missouri where volunteer enthusiasm will be needed to overcome state government resistance to implementation. Most of the events were intentionally small-scale — house parties, leafleting near a beach or a farmer’s market, not big rallies.

But in some ways, this suburban community 20 miles from Washington, D.C., captures the national ambivalence about the health law. Centreville is perched on the edge of two congressional districts, a red one represented by Rep. Frank Wolf — an ardent Republican opponent of Obamacare — and a blue one by Rep. Gerry Connolly, one of the health law’s Democratic champions.

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The Centreville event’s lone attendee, Lynn Duvall of Fairfax, Va., told POLITICO that it was her family’s own medical burdens that fueled her passion for Obamacare. Duvall’s son Logan has Crohn’s disease and under the law’s provisions can stay on her health plan until he turns 26, next January. Then he’ll be able to get coverage in the health exchange, despite his pre-existing condition.

Without Obamacare, she said, her son’s illness could have devastated their family finances.

“If the Affordable Care Act weren’t there, we would just have to deal with it. If it means we lose all of the assets we’ve saved over our lifetime, that’s what it would be,” said Duvall, who added that she left full-time work to care for her ailing son and aging mother, who she said was on Medicare and Medicaid before passing away at 103. “I would be really panicked if it weren’t for [Obamacare]. I don’t know what he would do.”

The OFA event’s organizer, 23-year-old Toora Arsala, a Northern Virginia Community College student, said the law is important to him because he has a variety of ailments and has relied on Medicaid for coverage.

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Backers of Obamacare are hoping to generate enough of their own events this summer to counteract any repeat of August 2009, when tea party activists swarmed town hall meetings to try to stop what was then still a health reform bill with a shaky future in Congress.

The tea party did come close to stopping it that summer — and it and its allies in Congress are planning its own high-profile August messaging campaign, promising street rallies, protests, and a reinvigorated call to dismantle Obamacare. It’s a last-ditch push for it as enrollment starts in October, and conservatives are eyeing this fall’s federal-funding battles as their best hope for putting on the brakes.

“The American people don’t want this law,” Jenny Beth Martin, co-founder of Tea Party Patriots, told reporters last week. Martin said her organization would fan out to congressional town halls in August, host a series of street demonstrations and take aim at any lawmaker who won’t support repealing or defunding the law.

Asked whether the full-throttle posture of both sides bodes for an intense August, Martin said she expects “heated debate.”

“Heated debate is what the First Amendment is about, and I think that as Americans we all want peaceable debate and discussion in America — both parties, both sides.” she said. “I have every reason to expect it.”